Boom tip



United States Patent 3,139,992 BOOM TIP Raymond .i. Wacht and Paul A. Lindahl, Overland Park, Kans., assignors to Pitman Manufacturing Company, Grandview, Mo., a corporation of Missouri Filed Feb. 18, 1963, Ser. No. 259,099 Claims. (Cl. 214-3) This invention relates to boom structure and, more particularly, to a boom for handling poles or the like.

It is the primary object of the present invention to provide a shiftable boom having pole-retaining means thereon adjacent one end thereof in the nature of sheave and cable structure to draw the pole against the end of the boom, the boom being configured to permit movement of the pole into any one of a number of angularly disposed positions relative to the longitudinal axis of the boom without having to alter the tension on the poleretaining cable such as by rotating the sheave.

A further object of the present invention is the provision of tip structure for a shiftable boom of the type described wherein said tip structure is provided with a boom-engaging peripheral surface lying along a line coincident with the involute of the circle defined by the outer surface of the sheave, whereby poles retained by the cable and sheave structure may be shifted relative to the boom without altering the tension on the cable.

Still another object of the present invention is the provision of a pair of spaced, boom tip members secured to and extending outwardly from one end of a shiftable boom of the type described and wherein each of the members is provided with an arcuate, transversely convex, peripheral surface for engaging a pole or the like, whereby the pole may be shifted relative to the boom into any one of a number of positions by sliding the pole over the surface notwithstanding the fact that the tension on the cable retaining the pole is maintained at a predetermined value.

Other objects of this invention will become apparent as the following specification progresses, reference being had to the accompanying drawings, wherein:

FIGURE 1 is a side elevational view of one end of a boom and illustrating a boom tip member thereon at the end for providing a pole-engaging periphery for the boom, and further showing power means at the end of the boom for rotating a sheave carried by the member;

FIG. 2 is a top plan view of a pair of members at the end of the boom and illustrating the sheave between the members in coupled relationship to the power means carried by one of the members;

FIG. 3 is an end view of the boom looking in a direction along the boom;

FIG. 4 is a fragmentary, cross-sectional view of the structure interconnecting the sheave to the power means; and V FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 3.

The present invention includes a boom for handling poles or the like such as poles for stringing telephone or high voltage electrical wires. The boom is configured to permit the poles to be picked up off the ground and moved into vertical positions so that the pole may be placed permanently into the ground.

The boom includes a pair of tip members at one end thereof which extend outwardly therefrom and provide journals for mounting a rotatable, cable-carrying sheave. Each mmeber is provided with a peripheral surface lying along a line coincident with the involute of the circle defined by the outer surface of the sheave. Thus, when the cable carried by the sheave is maintained under tension to draw the pole against the surfaces, the pole may be moved into any one of a number of locations angularly disposed relative to the longitudinal axis of the boom while the tension on the cable is maintained at a predetermined value. This construction, therefore, precludes having to rotate the sheave to compensate for the shifting of the pole relative to the boom.

Power means is carried by the boom adjacent one of the tip members for rotating the sheave. The boom engaging-surfaces are transversely convex to permit sliding movement of the pole over the surfaces.

The boom structure forming the subject of the present invention is broadly denoted by the numeral 10 and includes a shiftable boom 12, only one end of which is illustrated in FIGS. 1 and 2. Boom tip structure broadly denoted by the numeral 14 is carried by boom 12 at the normally outermost end of the latter. Power means 16 carried by tip structure 14 is operably coupled with a sheave 18 also carried by tip structure 14 for mounting a cable thereon.

Boom structure 16 is adapted for handling poles or the like, especially poles of the type for providing support for telephone or high voltage electrical wires. To this end, the cable carried by sheave 18 is adapted to be wrapped about a pole and to retain the latter against tip structure 14 when sheave 18 is rotated to apply tension to the cable.

Tip structure 14 includes a pair of tip members 20 and 22 which are secured at proximal ends thereof to the normally outermost end of boom 12 in any suitable manner such as by welding or the like. Members 20 and 22 extend outwardly from the boom in spaced relationship as is clear in FIG. 2. A plate 24 interconnects members 20 and 22 and serves to strengthen the joint between boom 12 and members 20 and 22. Each of the members 2i) and 22 is preferably formed from a casting and provided with webs 26 and 28 for enhancing the strength characteristics thereof.

Each of the members 20 and 22 is provided with a periphery broadly denoted by the numeral 30 and includes a pair of substantially longitudinally extending edges or surfaces 32 and 34 and an arcuate end edge or surface 36 interconnecting edges 32 and 34. As shown in FIGS. 2 and 3, end edge 36 has a substantially transversely convex surface generally facing outwardly relative to boom 12 and toward the adjacent member 20 or 22. As shown in FIG. 1, edge 36 merges smoothly with edge 34, the latter in turn extending to boom 12 in converging relationship with edge 32. It is clear that members 20 and 22 may be formed with the surfaces defined by edges 32 and 34 being substantially transversely convex in the same manner as end edge 36. The purpose of the convexity of edge 36 is to permit poles drawn against peripheries 30 to be able to slide into any one of a number of angularly disposed positions relative to the longitudinal axis of boom 12 without any appreciable interference from members 20 and 22.

The surfaces defined by edges 36 lie along lines coincident with the involute of the circle defined by the outer surface 38 of sheave 18. A portion of edge 34 forms a continuation of such line, but it is believed that for most applications the poles handled by boom structure 10 will very rarely be carried thereby with the longitudinal axis of the pole parallel or substantially so, with the longitudinal axis of boom 12.

By virtue of the construction of members 20 and 22, a cable wrapped in a clockwise sense about sheave 18, when viewing FIG. 1, may be wrapped under tension about a pole to draw the same against peripheries 30 so that the pole may be moved by sliding the same over edges 36 into any one of a number of angularly disposed locations relative to the longitudinal axis of boom 12 while maintaining the tension on the cable at a predetermined value. There is thus no need to rotate sheave 18 in either direction to compensate for the change in position of the pole, The pole may be manually moved by workmen standing adjacent to boom 12 while the boom 12 itself is shifted to raise the pole sufficiently above the ground for the purpose of transporting the pole to another position.

Sheave 18 is provided with a shaft 40 which extends through members 20 and 22. Suitable bearing structure (not shown) is carried by member 22 for journalling one end of shaft 40 and journal means (not shown) within a housing 42 secured in any suitable manner to member 22, rotatably mounts the opposite end of shaft 40. A pinion 44 is rigid to the opposite end of shaft 40 within housing 42 as is clear in FIG. 5.

Pinion 44 is in substantial mesh with a worm 46 within housing 42 and journalled by means of bearings 48 for rotation about an axis substantially parallel to the longitudinal axis of boom 12. A coupling 50 interconnects worm 46 with an output shaft 52 of a reversible prime mover 54 in the nature of a hydraulic motor or the like. Prime mover 54 is coupled with a source of hydraulic fluid so as to rotate shaft 52 in opposed directions. This permits shaft 40 to be rotated in opposed directions also to reel in or pay out the cable carried thereby. Prime mover 54 is preferably secured in any suitable manner to member 20 and is provided with a flanged neck 56 secured to a flanged collar 58 extending laterally from housing 42. Prime mover 54 is thus releasably secured to housing 42.

Sheave 18 is provided with a pair of spaced, annular flanges 60 defining the outer surface 38 thereof. Flanges 60 are disposed adjacent to and in close proximity with the inner surfaces of members 20 and 22. Member 20 is provided with an opening 62 therein which is slightly greater in diameter than the flanges 60 so that sheave 18 may be installed between members 20 and 22. To accomplish this, housing 42 is removably secured to member 20.

In operation, prime mover 54 is coupled with hydraulic lines emanating from a suitable source of hydraulic fluid. A cable is wound about sheave 18 and provided with means thereon for retaining a pole between members 20 and 22 and against peripheries thereof. When it is desired to move a pole from a horizontal position on the ground to a vertical position within a hole dug in the ground, boom 12 is shifted so that tip structure 14 is adjacent to the pole lying on the ground. The cable from sheave 18 is then wrapped about the pole and secured in any suitable manner so that the pole is moved against peripheries 30 when sheave 18 is rotated in a counterclockwise sense when viewing FIG. 1. Boom 12 is then elevated so that the lower end of the pole will clear the ground when the pole is caused to slide over peripheries 30 into a vertical position. When the pole is in this position, the boom may then be lowered to move the lower end of the pole into the hole dug in the ground.

It is to be emphasized that as the pole is caused to slide over peripheries 30 of members 20 and 22, the tension on the cable is maintained at a predetermined value. Thus, rotation of sheave 18 is obviated to maintain such tension on the cable, all of which is accomplished by virtue of the fact that edges 36 form involutcs of the circle defined by the outer surface 38 of sheave 18.

After the pole has been inserted into the ground and properly supported, the cable is removed from the pole and the boom 12 shifted to handle another pole in the same manner. It is also to be noted that sheave 18 may be rotated in opposed directions either to reel in the cable or pay the same outwardly of boom 12.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. Tip structure for a boom adapted for handling a pole, said structure comprising:

an assembly adapted to be secured to one end of a boom and provided with a pair of outwardly projecting, spaced tip members having peripheral, longitudinally arcuate surfaces configured to engage and retain a portion of a pole therebetween; and

a cable-receiving sheave carried by the assembly between said tip members and rotatable about an axis extending between the tip members, the pole engaging surfaces of the tip members lying in an imaginary, longitudinally arcuate envelope spaced from the axis of rotation of the sheave in partial surrounding relationship thereto and with the distance between the surfaces of the tip members and the axis of rotation of the sheave as defined by said envelope increasing progressively from one extremity of the envelope to the opposite extremity thereof by an amount to cause a cable trained over the sheave and secured to a pole against said surfaces to remain taut as the pole is shifted relative to said assembly and as a portion of the cable is caused to wind upon or unwind from said sheave.

2. Tip structure as set forth in claim 1, said envelope describing the involute of a circle having its axis coincident with the axis of rotation of the sheave.

3. Tip structure as set forth in claim 1, and means coupled with said sheave for releasably locking the latter against rotation to thereby cause a pole to be releasably maintained in a fixed position relative to said assembly.

4. Tip structure as set forth in claim 1, and including a pinion rigid to said sheave, a worm journalled in one of said tip members and disposed in meshing relationship to said pinion, and an actuatable prime mover coupled with said worm for rotating the latter and thereby said sheave in opposed directions, said prime mover being disposed for locking said worm and thereby said sheave against rotation when said prime mover is unactuated.

5. Tip structure as set forth in claim 1, each of said peripheral surfaces of said tip members being transversely convex to accommodate poles of different cross-sections.

References Cited in the file of this patent UNITED STATES PATENTS 1,908,146 Helton May 9, 1933 2,056,883 Brown Oct. 6, 1936 2,327,015 Carlson Aug. 17, 1943 2,598,517 Drott May 27, 1952 2,701,649 Hallstrom Feb. 8, 1955 FOREIGN PATENTS 64,096 Austria Mar. 26, 1914 

1. TIP STRUCTURE FOR A BOOM ADAPTED FOR HANDLING A POLE, SAID STRUCTURE COMPRISING: AN ASSEMBLY ADAPTED TO BE SECURED TO ONE END OF A BOOM AND PROVIDED WITH A PAIR OF OUTWARDLY PROJECTING, SPACED TIP MEMBERS HAVING PERIPHERAL, LONGITUDINALLY ARCUATE SURFACES CONFIGURED TO ENGAGE AND RETAIN A PORTION OF A POLE THEREBETWEEN; AND A CABLE-RECEIVING SHEAVE CARRIED BY THE ASSEMBLY BETWEEN SAID TIP MEMBERS AND ROTATABLE ABOUT AN AXIS EXTENDING BETWEEN THE TIP MEMBERS, THE POLE ENGAGING SURFACES OF THE TIP MEMBERS LYING IN AN IMAGINARY, LONGITUDINALLY ARCUATE ENVELOPE SPACED FROM THE AXIS OF ROTATION OF THE SHEAVE IN PARTIAL SURROUNDING RELATIONSHIP THERETO AND WITH THE DISTANCE BETWEEN THE SURFACES OF THE TIP MEMBERS AND THE AXIS OF ROTATION OF THE SHEAVE AS DEFINED BY SAID ENVELOPE INCREASING PROGRESSIVELY FROM ONE EXTREMITY OF THE ENVELOPE TO THE OPPOSITE EXTERMITY THEREOF BY AN AMOUNT TO CAUSE A CABLE TRAINED OVER THE SHEAVE AND SECURED TO A POLE AGAINST SAID SURFACES TO REMAIN TAUT AS THE POLE IS SHIFTED RELATIVE TO SAID ASSEMBLY AND AS A PORTION OF THE CABLE IS CAUSED TO WIND UPON OR UNWIND FROM SAID SHEAVE. 